Attention Deficit Hyperactivity Disorder (ADHD) Clinical Presentation

Updated: Mar 31, 2022
  • Author: Stephen Soreff, MD; Chief Editor: Glen L Xiong, MD  more...
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No physical findings have been well correlated with ADHD.

Mental Status Examination may note the following:

  • Appearance: Most often, appointments are difficult to structure and maintain due to hyperactivity and distractibility. Children with ADHD may present as fidgety, impulsive, and unable to sit still, or they may actively run around the office. Adults with ADHD may be distractible, fidgety, and forgetful.

  • Affect/mood: Affect usually is appropriate and may be elevated, but it should not be euphoric. Mood usually is euthymic, except for periods of low self-esteem and decreased (dysthymic) mood. Mood and affect are not primarily affected by ADHD, although irritability may frequently be associated with ADHD.

  • Speech/thought processes: Speech is of normal rate but may be louder due to impulsivity. Thought processes are goal-directed but may reflect difficulties staying on a topic or task. Evidence of racing thoughts or pressured speech should not be present. These symptoms are more consistent with a manic state (bipolar disorder).

  • Hallucinations or delusions: Not present.

  • Thought content/suicide: Content should be normal, with no evidence of suicidal/homicidal or psychotic symptoms.

  • Cognition: Concentration and storage into recent memory are affected. Patients with ADHD may have difficulty with calculation tasks and recent memory tasks. Orientation, remote memory, or abstraction should not be affected.

ADHD is associated with a number of other clinical diagnoses. Researchers from the CDC, the University of Florida-Jacksonville, and the University of Oklahoma Health Sciences Center found that more than half of children with ADHD also had another mental disorder, and these children were more likely to have other problems, such as struggling with friendships and getting into trouble in school or with the police. [19] Studies have demonstrated that many individuals have both ADHD and antisocial personality disorder (ASD). [20] These individual are at higher risk for self-injurious behaviors. ADHD is also linked to addictive behavior. The more severe the symptoms of ADHD, the greater the use of tobacco, alcohol, and marijuana. [21] Some individuals have both ADHD and an autism spectrum disorder. [22]  

Symptoms of ADHD and bipolar disorder may be directly correlated. Patients with ADHD should be assessed for possible underlying or coexisting bipolar disorder, and vice versa. [23]




Parents and siblings of children with ADHD are 2-8 times more likely to develop ADHD than the general population, suggesting that ADHD is a highly familial disease.

A study noted that ADHD had a 0.8 degree of inheritability and 80% of phenotypic variance could be attributed to genetics. [24]

Concordance of ADHD in monozygotic twins is greater than in dizygotic twins, suggesting some contribution of genetics. Studies estimate the mean heritability of ADHD to be 76%, indicating that ADHD is one of the most heritable psychiatric disorders.

The involved genes or chromosomes are not definitively known. Vulnerability to ADHD may be due to many genes of small effect. For example, several genes that code for dopamine receptors or serotonin products, including DRD4, DRD5, DAT, DBH, 5-HTT, and 5-HTR1B, have been moderately associated with ADHD.

ADHD risk is significantly increased in the presence of 1 risk allele in genes DRD2 (OR=7,5), 5-HTT (OR=2,7), and DAT1 (OR=1,6). ADHD risk is significantly increased at homozygotes for risk alleles in genes DRD2 (OR=54,8), 5-HTT (OR=6,7), and DAT1 (OR=6,6). [25] Another study implicated the following gene coding for ADHD: DRD4, DRD5, SLC6A3, SNAP-25, and HTR1B. [26]

Studies of cognitive deficits reveal another facet to the genetic contributions to ADHD. [27]


Hypotheses exist that include in utero exposures to toxic substances, food additives or colorings, or allergic causes. However, diet, especially sugar, is not a cause of ADHD.

How much of a role family environment has in the pathogenesis of ADHD is unclear, but it certainly may exacerbate symptoms.

According to one study, exposure to second-hand smoke in the home is associated with a higher frequency of mental disorder among children. Researchers undertook a cross-sectional study of 2357 children representative of the Spanish population aged 4-12 years in 2011-2012. Results showed that children exposed to ≥1 h/day of second-hand smoke had a multivariate odds ratio for ADHD of 3.14 compared to an odds ratio of 2.18 for children not habitually exposed to second-hand smoke. [28]

Personality factors

Although there remains much evidence for the genetic etiology of ADHD, one study indicated that the contribution of personality aspects in combination with genetics may be significant. Specifically, the presence of high neuroticism and low conscientiousness in conjunction with genetic vulnerability may constitute a risk factor in the expression of ADHD. [29]